Blast furnaces are used in the iron and steel industry for the production of pig iron which is later converted into steel and/or cast into a suitable form. The blast furnaces typically have refractory linings which protect their steel walls from oxidation, corrosion and erosion which would otherwise result from exposure to molten metal in the blast furnace. However, the refractory linings themselves experience wear and tear from exposure to the molten metal, and periodically have to be repaired or replaced.
The lining, or relining, of blast furnace interiors with a refractory material has conventionally been a time-consuming, labor-intensive, and relatively expensive process. Conventional lining methods have involved the use of preformed refractory bricks of predetermined size and shape which are adapted to conform to the contour of the blast furnace walls when the bricks are assembled together and stacked inside the blast furnace. The bricklaying methods have evolved into a complex science involving the selection of bricks of different sizes, shapes and compositions, for different regions in a blast furnace, and for different blast furnaces. Once the proper refractory bricks have been selected and formed, the bricks are laid side-by-side, and stacked vertically, in the blast furnace, and the joints between the bricks are filled with a refractory grout or slurry which then hardens and holds the bricks together.
U.S. Pat. No. 3,672,649, issued to Allen, describes a departure from the use of conventional bricks. A plurality of molding rings are installed, in sequence, in the blast furnace at a selected distance from the blast furnace steel wall. After the first ring is installed, a refractory lining material is manually poured between the steel wall and the molding ring, or is gunned into place. Then, a molding ring is placed at the next higher level in the blast furnace, and the above process is repeated until a monolithic refractory lining completely covers the desired region inside the blast furnace.
Unfortunately, manual pouring and gunning are also very labor-intensive and require much time to complete. Although a monolithic refractory lining is ultimately formed, it would be desirable to eliminate the need for preformed refractory bricks and the number of stages required to complete the manual pouring or gunning process. In the above-identified U.S. Pat. No. 3,672,649, no less than ten stages (represented by ten stacked molding rings) are shown in the drawings to form only a part of the desired monolithic refractory lining. As a result, the use of refractory bricks is still common notwithstanding the availability of this alternative process.